Production of alginic acid compounds



Patented July 9, 1946 if: UN ITED STATES PATENT OFFICE" I PRODUCTION OFALGmo Aom Y COMPOUNDS:

George Eric Cunningham,'Norman Henry Cham' V berlain, and John BamberSpeakman, Leeds,

England, assignors to Cefoil Limited; Maiden-f head, England, a Britishcompany J i c No Drawing. Application October 1,943, Se rial No.505,033. In Great' l$ritain .lulyl,

invention comprises improvements or I relating to the production ofalginic acid com DQunds. v V V Hitherto, it has been found extremelydifilcu-lt to prepareorganic derivatives of'alginic' acid when'simpleaqueous media are inadmissible (see, i011 gexampleefiirst, :JQnes and.Jon s, Jr em, Soc. 1939, page 1880). ,Theydifiicultyseemsto arise fromthe fact that the hydroxyl groups of alginic acid are so placed in thelong-chain molecules that they. are in closeproximity, with theresultothati hydrogen bond formation takes place,

alidlthe :compact structure so obtained .is inaccessible. ,to ornon-reactive with even comparatively smallmolecules of.--organicreagents. 5; According 'tothe present invention, in the pro,-

duction of organic derivativespf alginic acid,-;the

Y cording tofwel-l-known methods, e. g. those of' Miles, BritishPatent-No. 19,330 of. 1905; Dreyfus, French-Patent No.47 8,023 011914;:and Ost. Zeit.

angewnchem 1919', 32,- 68 wereacomple tely unsuccessful with air-dryfilaments although such methods are i known to besuccessful withcellulose. If,' however, 'alginic: acid yarn is soaked in water for atime to induce swelling, and. the- Waterthen displaced b glacial acetiacid; rapid acetyla'tioncan be brought about by: acetic. anhydride inpresence of. a 1 suitable catalyst, e.v g. sulphuric acid: Theprocesscan be applied to alginic acid 'in powder, film orfibrousvformk3.

P .The alginic acid yarn, soaked in-cwater atjroom temperature for saytwo hours, may betreated withzsuccessiveuchanges ,of glacial. aceticacid until the quantity. oi?v water retained by the yarn less-than-30.%- on theinltial air-dry weight of 40 a ousa ec1aims.(o1.2so-209.6) I

the, Thef as; results as obtained when the whole of the'wateris'rer'noyed; '---'I'he'iol1owing are examples of typical proceduresinaccordancewiththe invention: A

" i Example! V maize-yard neutron-1,0 gram) oi purified alginicacidya'rn is soaked in'water forlO minutes or more; lightlyrblotted' andtreated with'suc- 1 cessive 'lotsof glacial acetic acid in foursuccessive decantations of :30. cubic centimetres each over a period ofnot less than one hour.

1 'After drainingfofi rnost of the acetic acid, the

specimenisintroduced into"30 cubic centi metres" of, an acetylating.inixturejcontaining a non-solvent, follows:

. g g Grams Acetic anhydride j60 B nzene 1%" (a) The reaction may beallowed to proceed for -1' 7 2 l hours at C., and after purificationwith ben enaandeth r. c her ng yarn is white and lustrous, contains33.0% combined acetyl, and is 25 substantially soluble in aqueousacetone. Yield 95-98% of theory;

'(b) :A similar product is-obtained if the reaction is allowed toproceed foione hour at 25 (3., followed by a shorter period at a highertemperature (e. g. l5-30 minutes at 50 6 0 C.) i v 1- m ni ki t i@One'gram o'f alginic acidpowderis soaked in water for 10 minutes ormore and is then dehydrated as described in Example I with successivechanges of glacial acetic-acidf Lilian-treatmen w h 3 c c m es of Vithea etrla i s rea en setiqu j in Example or 24hours at 25' C awhiteproduct, soluble in etone, is obtained. w H

* Af'zoard hank (0,51-1'.0.gram) "or purified 9,1 ginic acid yarn issoaked'in water for 10 minutes 5101-1 more, and is subsequentlydehydrated, after light blotting,'with two successive lots'of 30 cubic'centim'etres'of absolute methyl alcohol over a tot r qd pqne u c Twentycub c ent metres o acetylating r 'jagentcontaining benzene, aceticanhydride, and

Eccample IV 6.5 grams air-dry alginic acid yarn is soaked for minutes ormore in a normal solution of sulphuric acid, and dehydrated with foursuccessive changes of 130 cubic centimetres glacial acetic acid over aperiod of not less than one hour. 7

Thus the catalyst is introduced during the presoak in water, Most of thecatalyst is removed in subsequent treatment to remove water, prior toacetylation but sufficient remains to iacilitate the reaction. Thismethod is valuable in preventing degradation.

Acetylation is carried out after draining off most of the aceticacid,"150 cubic centimetres of the following mixture being used for thepurpose:

. i Gram Benzene w H 139 Acetic anhydride 60 The, reaction is allowed toproceed for 2a hours at C;, or alternatively, for 1' hour at 25 C.followed by 15-30 minutes at 5060 C. The productis substantially thediacetyl derivative.

Example V 6.5 grams air-dry alginic acid yarn is soaked for it) minutesor more in a normal solution of perchloric acid, and dehydrated withfour successive changes of 130 cubic centimetres glacial 1 product isnot high (about 5% combined acetyl) but it is superior in handle andappearance to alginic acid yarn,

Example VII 1.5 grams air-dry alginic acid yarn is soaked in water for10 minutes or more, dehydrated with four successive changes of 50 cubiccentimetres glacial acetic acid, and, after draining, is treated with 50cubic centimetres of reagent of the following composition: I

Grams Benzene 180 Acetic anhydride 60 The reaction is allowed to proceedfor 48 hours at 40 0., when a product containing 10-12% combined acetylis obtained, which swells highly in water and which is dispersed bymixtures of water and acetone.

Example VIII 1.5 grams air-dry alginic acid yarn is soaked in Water for10 minutes or more, dehydrated with lowing composition:

acetic acid over a period of not less than one hour;

,Acetyl'ation maybe carried out after draining ofi mostof the aceticacid, 150 cubic centimetres of the following mixture being used for thepur- 'Grams Benzene 180 Acetic anhyd-ride 60 E wm z VI 125' grams or"air-dry alginic acid yarn is soaked in water fonlq'minutes or more,dehydrated with four successive changes of cubic centimetres glacialacetic acid, and'after draining is treated with 50 cubic centimetres ofreagent containing acetic anhydride and benzene, (but no catalyst)inthe, followin p po ion Grams Benzene j t 180 Acetic anhydride Thereaction is allowed to proceed for-one week at 20-25 C. and the productpurified with ben-- acne and ether. The degree of acetylation of the oursuccessive changes of 50 cubic centimetres glacial acetic acid and afterdraining, is treated with 50 cubic centimetresof reagentof the fol-Grams The reaction is allowed to proceed for 24-hours at 60- C;, when aproduct containing about 16% combined acetyl is obtained.

Example IX A.40-.yard hank ofpurified .alginic. acid yarn (1.65 gramsair-dry) is soaked for 10 minutes or more in a normal solution ofperchloric acid, drained free from excess moisture, and thendohydratedWith four successive changes of 50 cubic centimetres of glacial aceticacid over a period of one hour-or more. Excess acetic acid .is drained.ofi, and the material treated with the following mixture at 60 C. for 30minutes:

i I Grams. I Propioni'c anhydride 12 Benzene 36 ,The product isp ri ed wth n ne d e h to. remove traces oi the reagent. ,Itis a white lustrousyarn which m y b h ted t at least 60 C. witho t dis olouration,isseluble in, aqu ou acetone and in benzeneahach k mixtures. andsubstantially composed ofdinropi0ny1a1sin c acid 010% propion b. The. yeld is: 9 oithat theoretically obtainable, The above Examples .VI,processes where no catalyst: isemployed.

In Example III it will be. noted that; methyl a1,- cohol. is used todisplace water instead of glacia acetic acid,-.-. Other organic liquidsmay, beused for the'purpose; providing they are suflicientlllpolar-.to-rprevent re-association. of the hydroxyl groups of theaIginicacidwhen-othe waterisrce movecly .l l

7 Moreover-,- instead of displacing water: from the swollen .alginicacid by means. oi'glacialjacetic acid or methyl alcohol; it: could, beremoved by combination; thus, acetic anhydride could. be added, withcooling;to..,water-swollen. or; sulphuric-acid+solutioneswollenalginic'v acid: The water would thus be removed by combination withacetic anhydride to form. glacial acetic acid.

Finally the-principles described.- above. may be applied in; thepreparation of other esters/(the and VIIIIare of butyrate, for example)and mixed esters (theaceto-butyrate, for example).

We claim: 7

1. In the production of lower fatty acid esters of alginic acid, thesteps of first swelling the alginic acid in an aqueous medium for atleast 'ten minutes, then removing water from the swollen structure,while still maintaining the swollen state, by introducing anhydrophyllic organic liquid which is sufiiciently polar to preventre-association of the hydroxyl groups of the alginic acid when the wateris removed, and thereafter carrying out the reactions necessary. for theproduction of the desired lower fatty acid esters.

2. A process as claimed in claim 1 wherein the Water is removed bydisplacement with glacial acetic acid. I

3. A process comprising the steps set forth in claim 1 wherein removalof the water is effected by causing it to combine with an hydrophyllicorganic liquid which is introduced into the reaction mixture, saidhydrophyllic organic liquid being sufficiently polar toprevent'reassociation of the hydroxyl groups of the alginic acid whenthe water is removed.

a. A process as claimed in claim 1 wherein the reaction of the alginicacid, after swelling, is facilitated by the presence of a catalyst inthe reaction mixture.

5. A process as claimed in claim 1, whereina catalyst is introduced asan ingredient of the aqueous swelling medium.

6. In the production of lower fatty acid esters of alginic acid, thesteps of first swelling the alginic acid in an aqueous medium, thenremoving water from the swollen structure while still maintaining theswollen state, by introducing a hydrophyllic organic liquid of the classconsisting of lower fatty acids and their anhydrides which issufficiently polar to prevent re-association of the hydroxyl groups ofthe alginic acid when the water is removed, and thereafter carrying outthe reactions necessary for the production of the desired lower fattyacid esters.-

GEORGE ERIC CUNNINGHAM. NORMAN HENRY CHAMBERLAIN. JOHN BAMBER SPEAKMAN.

